A number of catalytic processes are employed in the petroleum industry for the purpose of converting crude petroleum to a variety of products having physical and chemical properties which make them suitable for use by consumers. Among the refining processes involving the use of catalysts are cracking, hydrocracking, hydrodesulfurization, hydrodenitrification and reforming. In these and other refining processes where catalysts are employed, the catalysts decline in activity during the course of use as a result, in major part, of accumulation of carbonaceous matter commonly containing hydrogen and sulfur on the catalyst surface and in the catalyst pores. A number of catalysts used in a number of processes lose activity rapidly during the course of use and ordinarily the plants in which such catalysts are employed have provision for regeneration of the catalyst either in the reaction vessel itself or in an adjacent regenerator vessel to which the catalyst is transferred continuously as it is used. A number of catalysts, however, are used for extended periods before they become deactivated and continue to be effective until the build-up of carbonaceous material on the catalyst is very high. Onstream periods of months, or even years, are observed in some of the processes. In these cases, the refining units do not ordinarily include provision for catalyst regeneration and the refiner simply discards the catalyst when it has completely lost activity and replaces it with a new charge or the catalyst may be removed from the refining unit and regenerated in a regeneration unit which is neither attached nor related to the refining unit from which the catalyst is taken.
Catalysts containing cobalt, nickel, tungsten, molybdenum, or mixtures of two or more of these metals supported on a conventional support such as alumina, are commonly employed in hydrodesulfurization of various petroleum streams, hydrodenitrification of such streams and in hydrocracking high boiling petroleum streams which are previously treated to reduce sulfur and nitrogen contents. These catalysts are commonly used for extended periods before they become so deactivated by accumulation of carbonaceous deposits that they must be replaced. Theoretically, these catalysts can be regenerated by burning the carbonaceous deposits from the catalysts' surfaces and so restoring catalyst activity to a level about 90 percent of the activity of a fresh catalyst charge. Heretofore, no great amount of these catalysts have been regenerated because of difficulties experienced in the course of the regenerating procedures applied. Commonly, it is attempted to regenerate these catalysts in fixed beds by passing hot gas having a very low oxygen content through the bed to burn the carbonaceous material from the catalyst. Hot spots commonly develop in the fixed beds with resultant sintering of the catalyst and formation of large catalyst clinkers. It has also been proposed to regenerate these catalysts by passing them through a rotating kiln similar to a cement kiln and in this method considerable attrition of the catalyst by breakage and poor contact of the regeneration gas with the catalyst surface leads to low catalyst recovery and to a rather poor level of reactivation.
The present invention provides a means for regenerating heavily contaminated catalysts and obtaining high yields of highly reactivated material. The cost of reactivating these catalysts pursuant to the present invention does not ordinarily exceed about one-fourth of the cost of fresh catalyst and this cost includes transportation charges.